One way Drain valve at back of boat?

BruceK's post reminded me about a thought about the drain plug on eve1's boat.
By design of boat type i think it would be fair to say it does not fill up with water in normal use so any self bailer could be a compromise to its watertightness. Self bailers are more common on sailing dingys that don't sink when full of water.
But why is the outside part of the drain plug on the inside?
A planing hull at speed would empty the inside if the plug was removed . I'm sure your tender would too if you could go fast enough.
It's possibly a design idea to be able to drain and replace whilst under way ?
I would like to know what's on the outside, a valve ?maybe just the hole ?
There are a lot of 16ish feet boats moored outside where I live. Most that have fitted some sort of self bailing devices end up sinking ! Even elephants trunk type have sunk.
 
Wow, lots of posts while I was writing. I've never seen an internal one before but seen many external.
Seastoke, did yours have any non return valve or was it just a hole?
Did you have a deck with sump or open hull ?
 
Rappey said:
Wow, lots of posts while I was writing. I've never seen an internal one before but seen many external.
Seastoke, did yours have any non return valve or was it just a hole?
Did you have a deck with sump or open hull ?
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no none return and open hull , we launched in the dart one night to watch the fire works , in the dark half way down the river we had 3 inch of of water , shit myself then realized had not screwed bung in.
 
Amanzi has a bung on the outside, You can see it (removed) on the keel. Your boat has a bung on the inside? Why am I not surprised :ROFLMAO:

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Boats often have decks which seperate the interior from the void in the v hull .
Like the pic above, externally is sometimes the only way to get to it.
Think like a rib. It has a sump and pump at rear, but the external plug will drain the hull, not the interior or sump.
With an open hull then it can be accessed from the inside
 
I find myself (unusually!) agreeing with Seastoke. I think it is a bung you remove when the boat is out of the water to drain any remaining water out when you put it back on the trailer, and to stop rainwater filling up the cockpit when it's out of the water (which as well as inconvenient puts excessive loads on the trailer and on the boat where it is supported by the trailer).

I suggest you take it out for the first time only when the boat is out of the water. As it is now siezed, the force you need to extract it may well damage either the bung or its housing. Once it is out get yourself a spare (as well as a new one if needed). If you can't find a bung to match, you'll have to replace the whole bung and housing fitting.
 
LittleSister said:
I find myself (unusually!) agreeing with Seastoke. I think it is a bung you remove when the boat is out of the water to drain any remaining water out when you put it back on the trailer, and to stop rainwater filling up the cockpit when it's out of the water (which as well as inconvenient puts excessive loads on the trailer and on the boat where it is supported by the trailer).

I suggest you take it out for the first time only when the boat is out of the water. As it is now siezed, the force you need to extract it may well damage either the bung or its housing. Once it is out get yourself a spare (as well as a new one if needed). If you can't find a bung to match, you'll have to replace the whole bung and housing fitting.
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Hello , what do you mean, sister.
 
Rappey said:
But why is the outside part of the drain plug on the inside?
A planing hull at speed would empty the inside if the plug was removed . I'm sure your tender would too if you could go fast enough.
It's possibly a design idea to be able to drain and replace whilst under way ?
Click to expand...
The above is correct, (remember we are talking small boats) one small boat that has plugs outside is the CJR, it has three, one for each keel, these are used to drain when out of the water, four boats i have owned, Shetland Sealark, Alaska, Icelander, Argo Hellas, all had a bung on the inside, you could swill the deck whilst underway with the bung out, when you stop, water would come in, you have to remember that these bungs were at deck level, they did not drain the bilge area below the deck, some boats have an external bung for this, or it can be in the transom/deck well, if it is in the well, it will also drain underway.
 
Refueler said:
Flapper valves only close with positive pressure against them and are notoriously unreliable.

Personally I would not rely on it and would fit something like I have in my ex Soviet boat. I have a small float switch bilge pump ... 12V 7A/Hr SLA battery and a 10W solar panel ... no regulator or fancy bits needed.
Pump sits in the bilge, pipe overboard ... solar panel keeps battery charged ... float switch switches pump on / off as needed.

Using something like that - basically can ignore the flapper / bung affair ...
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Refuler, I did your set up of Blige pump, battery and solar panel. But the battery connection wasnt good so I came back to a boat full of rainwater! I tightened up the connections and pump ran so its ok for now. Incidentally the previous owner did seal the bung in. That bung is just below the waterline! I dont like the design!

If I buy a better boat I would prefer one which is self draining
I saw a Quicksilver 510 which seemed to have the inside of the boat higher than the waterlevel, and hence just a simple drain hole looks to drain that, without a pump.
Am I right about that, are many small motorboats self draining?
 
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